The liverwort genera (Bryophyta: Hepaticae and Anthocerotae) of Britain and Ireland

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L. Watson and M. J. Dallwitz

Aphanolejeunea Evans

~ Cololejeunea.

Gametophyte. Plants very minute, filiform, translucent, pale green, scattered, gregarious or in small thin patches leafy. The shoots procumbent, sparsely irregularly branched, the female inflorescences terminal but becoming pseudo-lateral by growth of subinvolucral innovations. The branching more or less of the Radula type (but the branches without a basal collar). Acrogynous. The leaf cells without trigones. Rhizoids present (rather scarce, quite long); of one kind, all smooth.

The leafy shoots dorsiventral, with the two ranks of laterals more or less equal in size and the ventral rank lacking. The vegetative leaves alternate; distant; erecto-patent, the rounded keel crenulate with bulging cells, unequally bilobed (the dorsal lobe very convex, apically obtuse to acute, its margins smooth to crenulate with bulging cells, the ventral one smaller but more than half as long and folded under the dorsal, inflated, its free margin incurved, its apex a 1–2 celled tooth with another inconspicuous tooth beside it); complicate-bilobed; leaves keeled proximally to the lobes. The ventral lobes much smaller than the dorsal ones; with a stylus (this unicellular, ephemeral). The vegetative leaves without vittae. The cells of the gametophyte with numerous small chloroplasts. Gemmae common to rare (discoid, multicellular, arising on leaf lobes at right angles to the margins).

The plants bisexual; having the gametangia grouped into bracteate inflorescences; paroecious.

Male inflorescences of two bracts proximal to the females, similar to the leaves. Female inflorescences terminal becoming pseudolateral via a subinvolucral innovation. Female bracts present (larger than the leaves, unequally bilobed and more or less conduplicate, the margins crenulate). Perianth present (longly exserted, obpyriform, terete, without angles, smooth below, coarsely papillose above, the apex truncate with a short beak). Perianth distally smooth, not plicate. Perianth distally beaked.

Sporophyte. The sporophyte elevated by elongation of the seta, with no intercalary meristem. The capsule ovoid; brown, not green. Elaters present; unispirally thickened; persistent on elaterophores (orientated vertically in the unopened capsules and extending to the floor, remaining attached by their upper ends to the inner walls of the distal ends of the dehiscing capsule valves and their trumpet-shaped lower ends becoming free).

British representation. 1 species (A. microscopica); England, Wales, Scotland, and Ireland.

Classification. Class/Division Hepaticae. Subclass/Class Jungermanniidae. Order Jungermanniales. Family Lejeuneaceae.

Illustrations. • A. microscopica: Jameson, in Macvicar (1926). • A. microscopica (as Lejeunea): Pearson fig. XIX (1902). • A. microscopica (as Lejeunea): Pearson fig. XIX, legend.

To view the illustrations with detailed captions, go to the interactive key. This also offers full and partial descriptions, diagnostic descriptions, differences and similarities between taxa, lists of taxa exhibiting or lacking specified attributes, and distributions of character states within any set of taxa.

Cite this publication as: ‘Watson, L., and Dallwitz, M.J. 2005 onwards. The liverwort genera (Bryophyta: Hepaticae and Anthocerotae) of Britain and Ireland. Version: 24th February 2016.’.